Engine HP (horsepower) is the amount of power the tractor’s engine generates. Whereas, the PTO power is the power generated by the tractor to the attached implement after losing some power between the tractor and the PTO shaft and which is then transferred to the attached implement. Furthermore, the attached implement that drains some of the horsepower from your engine includes your hydraulic pumps, power steering, and hydrostatic drive. These parts of the tractor are responsible for transferring the horsepower from the engine to the PTO shaft. Hence, this proves that a 40 HP engine cannot run an implement requiring 40 HP PTO. PTO HP always remains less than your engine horsepower.